The following disclosure relates generally to medical devices, systems and methods, including, for example, a bone screw system and a method of using it in surgery.
A variety of support assemblies currently exist which may be surgically implanted into a patient's intervertebral space so as to provide support between two (or more) adjacent vertebrae. Surgical implantation of such systems is typically used to provide support along the spinal column in cases where a portion of the patient's intervertebral anatomy has become diseased or destroyed. In addition, such support systems are also commonly used following a discectomy, wherein the patient's intervertebral disc is surgically removed.
Most commonly, existing support systems typically operate by inhibiting normal movement between the adjacent vertebrae, thereby holding these vertebrae at fixed positions relative to one another, with the mechanical body of the supporting structure providing the needed support along the patient's spinal column. Such supporting systems are typically made of stainless steel or titanium, and are designed to permanently remain within the patient's body.
It is beneficial, in addition to fixation, to try to stimulate bone growth between the adjacent vertebrae. To do so, spine surgeons use bone graft material in addition to fixation devices. Bone graft doesn't heal or fuse the spine immediately; instead, bone graft provides a foundation or scaffold for the patient's body to grow new bone. Bone graft can stimulate new bone production. When new bone grows and solidifies, fusion occurs. Although instrumentation (e.g., screws, rods) is often used for initial stabilization (post-operative), it is the healing of bone that welds vertebrae together to create long-term stability.
There are two general types of bone grafts: real bone and bone graft substitutes. Real bone can come from the patient (autograft) or from a donor bone (allograft). Also used in these types of surgery are bone substitute, osteoinductive agent, and bone cement. There is a need for alternative systems and methods that use both fixation and fusion.